build server was running Ubuntu 16.04.4 LTS local.conf was excerpted as below, PREFERRED_PROVIDER_virtual/kernel = "linux-yocto-rt" WRTEMPLATE ?= "feature/initramfs" WRLINUX_BRANCH = "LTS" INHERIT += "rm_work" PACKAGE_INSTALL_append_pn-wrlinux-image-initramfs = " lrzsz" TOOLCHAIN_TARGET_TASK_append = " python-dev kernel-dev kernel-devsrc" TOOLCHAIN_HOST_TASK_append = " nativesdk-openssl-dev nativesdk-bison nativesdk-flex"